Calculator App

A Simple Calculator using Java Servlet with shared access to calculation history of clients. The max records to display is capped to 10.

Concepts Used

• TCP Sockets for communication between client and server

• Synchronized threads to access calculation history of all clients

• Java Servlet to build the UI (Running on TomCat Server)

Concepts Used

• TCP Sockets for communication between client and server

• Synchronized threads to access calculation history of all clients

• Java Servlet to build the UI (Running on TomCat Server)

Execution Steps in IDE

• Bring up the server by executing CalcServer file.
• Run webapp project on Tomcat. This display the GUI as shown in below screenshot.
• To perform calculations, access the GUI through URL: http://localhost:8080/sharedCalculatorWebApp/index.jsp

Execution steps without IDE

Prerequiste softwares : Java, Tomcat(installation steps provided below) 

Server

• Download server's executable jar file to run calculator server.
• Run the server using java -jar calcServer.jar command in the run console/terminal.

Client

• To run the client, Tomcat is required. If you dont have it installed, follow below steps for Tomcat installation:
  • Download Tomcat from here
  • After downloading, unzip the folder and open terminal/console in the folder location
  • In terminal, run the command chmod +x ./bin/startup.sh to grant permissions
  • Run the command chmod +x ./bin/catalina.sh
• Once Tomcat is installed, Place war file(sharedCalculatorWebApp.war) in webapps folder of Tomcat
• Start Tomcat using ./bin/startup.sh
• Open the URL: http://localhost:8080/sharedCalculatorWebApp/index.jsp to access the calculator

Screenshot of the UI

Decsription

A web app (in java) to log calculations as they happen and shares those calculations with everyone connected to the website.

For example, user A and user B go to your site at the same time. User A calculates "5 + 5", which equals "10". This is logged below the calculator as "5 + 5 = 10". User B is updated about this calculation right after user A posts it. Now, user B calculates "3 x 4".This calculates to “12” and displays "3 x 4=12" right below the prior calculation. User A sees this update immediately after user B posts it.

Results remain between sessions. Only last 10 calculations descending from most recent to oldest are displayed the history

Limitations of the app

• The calculator can perform only +,-,x,/ operations
• It can take values only in the range of double data type